Despite Sauber suffering yet another engine failure in China on Sunday, the fingers of blame did not immediately point in Ferrari's direction.

Despite Sauber suffering yet another engine failure in China on Sunday, the fingers of blame did not immediately point in Ferrari's direction.

After engine overheating problems in Bahrain, Fernando Alonso's retirement and two Sauber failures in Malaysia, and then a practice blow-up for Alonso in Shanghai practice, the 2.4 litre unit in de la Rosa's C29 then expired in the early stages of the Chinese grand prix.

Having dodged the strategy chaos to be running fourth, the failure was particularly bitter for the Spaniard and the struggling Swiss team.

"The team and the driver did everything right," Peter Sauber told Germany's Auto Motor und Sport.

Ferrari didn't mention the failure in its official post-race report, while Sauber said de la Rosa suffered a "technical failure" with a cause that "still needs to be analysed".

Said new technical director James Key: "It is engine-related but we can't say whether it's a specific engine problem or a problem related to the chassis."

As for the currently uncompetitive C29 car, Key admitted his early impressions were not all good.

"It's a very well-built car, but there are some areas that we need to work on," the former Force India man is quoted as saying.